package javax.obex;
/**
 * This interface provides a way to respond to authentication challenge and
 * authentication response headers.  When a client or server receives an
 * <code>onAuthenticationChallenge()</code> or
 * <code>onAuthenticationResponse()</code> will be called, respectively, by
 * the implementation.
 * <P>
 * For more information on how the authentication procedure works in OBEX,
 * please review the IrOBEX specification at
 * <A HREF="http://www.irda.org">http://www.irda.org</A>.
 * <P>
 * <STRONG>Authentication Challenges</STRONG>
 * <P>
 * When a client or server receives an authentication challenge header, the
 * <code>onAuthenticationChallenge()</code> method will be invoked by the
 * OBEX API implementation.  The application will then return the user name
 * (if needed) and password via a <code>PasswordAuthentication</code> object.
 * The password in this object is not sent in the authentication response.
 * Instead, the 16-byte challenge received in the authentication challenge is
 * combined with the password returned from the
 * <code>onAuthenticationChallenge()</code> method and passed through the MD5
 * hash algorithm.  The resulting value is sent in the authentication response
 * along with the user name if it was provided.
 * <P>
 * <STRONG>Authentication Responses</STRONG>
 * <P>
 * When a client or server receives an authentication response header, the
 * <code>onAuthenticationResponse()</code> method is invoked by the API
 * implementation with the user name received in the authentication response
 * header.  (The user name will be <code>null</code> if no user name was
 * provided in the authentication response header.)  The application must
 * determine the correct password.  This value should be returned from the
 * <code>onAuthenticationResponse()</code> method.  If the authentication
 * request should fail without the implementation checking the password,
 * <code>null</code> should
 * be returned by the application.  (This is needed for reasons like not
 * recognizing the user name, etc.)  If the returned value is not
 * <code>null</code>, the OBEX API implementation will combine the password
 * returned from the <code>onAuthenticationResponse()</code> method and
 * challenge sent via the authentication challenge, apply the MD5 hash
 * algorithm, and compare the result to the response hash received in the
 * authentication response header.  If the values are not equal, an
 * <code>IOException</code> will be thrown if the client requested authentication.
 * If the server requested authentication, the
 * <code>onAuthenticationFailure()</code> method will be called on the
 * <code>ServerRequestHandler</code> that failed authentication.  The
 * connection is <B>not</B> closed if authentication failed.
 */
public interface Authenticator {

	
	/**
	 * Called when a client or a server receives an authentication challenge header. 
	 * It should respond to the challenge with a {@link PasswordAuthentication} that 
	 * contains the correct user name and password for the challenge.
	 * 
	 * @param description the description of which user name and password should be 
	 * used; if no description is provided in the authentication challenge or the 
	 * description is encoded in an encoding scheme that is not supported, an empty 
	 * string will be provided

	 * @param isUserIdRequired {@code true} if the user ID is required; {@code false} 
	 * if the user ID is not required
	 * @param isFullAccess {@code true} if full access to the server will be granted; 
	 * {@code false} if read only access will be granted
	 * @return a {@link PasswordAuthentication} object containing the user name and 
	 * password used for authentication
	 */
	public PasswordAuthentication onAuthenticationChallenge(java.lang.String description,
            boolean isUserIdRequired,
            boolean isFullAccess);
	
	/**
	 * Called when a client or server receives an authentication response header. This 
	 * method will provide the user name and expect the correct password to be returned.
	 * 
	 * @param userName the user name provided in the authentication response; may be 
	 * {@code null}
	 * @return the correct password for the user name provided; if {@code null} is 
	 * returned then the authentication request failed
	 * 
	 */
	public byte[] onAuthenticationResponse(byte[] userName);
	
	
}
